Electric generator.



PATBNTED AUG. 11, 1908.

J. L. WOODBRIDGE.

ELECTRIC GENERATOR. APPLICATION FILED D110. '1, 1907.

WITNESS: I N VEN TOR.

( .lsephlester-kib'ad'b r- 'dge.

W QEXo w.

" ATTORNEY.

' 1 j No. 895,324,

UNITED STATEALPENT ()FFICE.

JOSEPH: LBSTER-WOODBRIDGE, OF PHILADELPHIA, PENNSYLVANIA.

ELECTRIC GENERATOR.

Specification of Letters Patent.

' Patented Aug. 11, 1908.

Application filed December 7, 1907. Serial Not 105,588.

allwhom itmay-concern:

- Be it known that I, JosEPH LESTER WOOD- BRr-DGE, acitizen of the United States, and res dent of Philadelphia, in the. county of Philadelphia and State. of Pennsylvania,

.Jhave inventedlcertain new and usefdllm- 'provements in Electric Generators, of which .thefollowing is a specification. I

The'object-of the resent'invention is to provide meansv for 'o taining two different potentials from one armature winding and commutator, and'to provide means for controlling the two"; potentials independently To these and other ends hereinafter set forth the invention comprises the improvements-to be presently described and finally claimed.

. The nature, characteristic features and- .sc'ope of the invention will be more fully understood from the-following description [takenin connection with the accompanying drawings forming part hereof, and in which- Flgure 1, 1s a general View of a direct ourrent generator embodying'features of themventron, and F1g.:2 ,illustrates the armature.

winding of the generator shown in Fi'gf l; In. Fig. 1, F,'-is the field frame and D, the armature of a direct current generator; :The

field circuit is garovided with three poles S, N

and N ,looate at equi-distant points around the armatureperiphery. E, is thecommutator of this 'generator andbearing-upon the commutator are three brushes A, B and The armature winding ,which willbe described.

later in connection with Fig. '2, is so designed that the difference of-potential between the v brushes C and-A," and that betweenthe ,pendently; As here shown the oles, is of .40

brushes C; and B, may be controlledinde south polarity, while the poles-o N and N are both of north polarity; The total magtrolled by three fie d windings. One of these windings 5, is wound on all three poles and is connected in shunt between the brush 0 andthe brush A, arheostat'R being connected I i intothiscircuit for controlling the current in this winding in the usual manner. This winding will control the total flux in the entire field circuit and with this winding alone the flux would be equally divided between N and N A second field winding 6, is shown wound only on the poles N and N", and connected in shunt between the brushes C and A, with the rheostat R in circuit.

The efiect of this winding is-to increase the flux'in N and. decrease that in N, thereby roducing a hi her potential between the brushes B and and a low er potential between the brushes A and C,'than would otherwise exist. The third'winding'7, is connected in series between the brush A and the conductor 2', and is so designed that an increase of current in conductor 2, passing through this winding, will increase the potential between the brushes C and A, and decrease'the potential between the brushes C- and'B..

Fig. 2, illus'l rat es diagrammaiica-lly in the usual mannert he method of windi-ngihe arma'ure of. the generator shown in Fig. 1.

Rectangular areasJS, N and Ni represent the pole faeeso'f'the generator, while A,1B,

and C, repre senti the.three'brushes; Starting from thepoint 11, in the armature winding underbrush'B and following the winding through the conductors I), a, d, c, f, e, h, g, j, i,"to the point 12 under thebrush B, it will be not ed that this. port ion of the armature winding is affected by the flux in poles N and S only, and that .t he eleciro-motiveforce developed in each of the conduct ors un- .de'r these pole faces will be cumulative and produce a iotal elect ro-moiive-force between the brushes B and C, proportional to the sum of 'i'the magnetic flux in S, and that in Similarly'it will be seen, that the potential be'weeni'he brushes C 'andAwill be propor- A and B will be proportional-to the difference between the flux in .N and that in N.

are therefore developing no 0 octro-moiive- It will be noted-also that Hie-conductors 7c and .m, which constitute the armature coil short circuited by l he brush'B,'are passing through the neutral area between ihetpole faces and,

tional to thetotal flux in S and N On .the I other handthe potential between the brushes force. iThe; same is true of the coils short circuited by the brushes C and A. This 'arrangement will therefore permit satisfactory commutatlonlo be secured. What I claim is:

1.. A generator polo frame provided with polar projections in groups of three; field windings adapted to produce in each group magnetic llux of likepolarity in two of the.

i like polarity; and an armature. 111 operative relation to the field poles and Pl'OVlt ed with a winding, commutator and brushes so disposed that the armature coils between any pair of brushes are acted upon by the flux in only two poles in each group of three.

2. A generator pole frame provided with polar projections in groups of three; field windings adapted to produce in each group magnetic ilux of like. polarity in two of the poles of said group and in the third a flux equal to the sum of that in the of her two and of opposite polarity; and an armature in op- I'tLiIVG relation to the field poles and provided with a winding, commutator and brushes so disposed that the armature coils between any pair of brushes are acted upon by the 'l'lLlX. in only two poles in each group of three.

3. A generator pole frame provided with polar projections in groups of three, field windings adapted to produce in each group amagnetic flux of like polarity but of unequal st rcngth in two of the poles of said group and in the third a flux equal to the sum of that in the other two and of opposite polarity, and an armature in operative relation to the hold poles and provided with a winding, commutator, and brushes so disposed that the armature coils between any pair of brushes are acted upon by the flux in only two poles of each grou of three.

4. A field frame for a dynamo electric machine provided with poles of which more are of one polarity than are of the opposite polarity, means for producinga magnetic flux unequally distributed between the first men tioned poles, and an armature with its commutator and brushes adapted to develop unequal electromotive-forces between the. brushes when the armature is revolved in the unequally distributed flux.

5. In combination a field frame for a dynamo electric machine provided with poles of which twice as many are of one polarity as are of the opposite polarity, means for producing an unequal distribution of magnetic flux between the more numerous poles of the same polarity, and an armatureprovided with commutator and three sets of-brushes therefor adapted to develop unequal differences of potential between the different sets of brushes when the arn'iature is rotated in the unequally distributed flux.

' In testimony whereof I have hereunto signed my name.

JOSEPH LESTER WOODBRlllGE.

\Vitnesses:

FRANK E. FRENCH.

K. M. GILLIGAN. 

